The present invention relates to a printer provided with printing means, such as a daisy wheel, adapted to be opposed to a printing sheet or other printing medium to effect printing thereon.
In printers of this type, a plurality of mechanisms are used to perform various operations associated with a printing operation. Where the printing means of one such printer is formed of a daisy wheel, for example, these mechanisms include a hammer actuating mechanism which causes selected types on the wheel to impact against a printing medium on a platen. The mechanisms further include a ribbon feed mechanism for feeding a printing ribbon between the platen and printing means, and a sheet feed mechanism for feeding the printing medium line by line. In a printer having a function to correct printed characters, i.e., so-called correcting function, a correction ribbon feed mechanism is combined with a correction ribbon lift mechanism which serves to raise a correction ribbon from a normal or pause position to a printing position. These mechanisms are adapted to be actuated by a driving force supplied from drive source means. However, the driving characteristics, including rotational load and rotating speed, required for the operation of one mechanism are different from those for the operation of another.
In the prior art printers, therefore, a plurality of drive motors are used to operate the individual mechanisms. The mechanisms are divided into several groups by the driving characteristics, and a common motor is provided for each group.
In this case, however, so many motors are used in each printer that the manufacturing cost is very high, and the necessary space for the motors is too wide to provide a compact design.
Meanwhile, an arrangement has been proposed in which a single drive motor is coupled to the various mechanisms by means of reduction gear systems so that different rotating speeds are provided for the individual mechanisms as required.
However, the proposed arrangement requires complicated reduction gear systems, resulting in sophisticated printer construction, increase in number of components, and higher manufacturing cost. Moreover, an additional space is needed for the gear systems, constituting a hindrance to the miniaturization of the printer.
Conventional printers of the proposed arrangement are subject to a further drawback that the reduction gear mechanisms produce substantial noises during operation.
One such printer is disclosed in U.S. Pat. No. 3,825,103.